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moby--moby/pkg/plugins/client.go

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package plugins
import (
"bytes"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"strings"
"time"
"github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/sockets"
"github.com/docker/docker/pkg/tlsconfig"
)
const (
versionMimetype = "application/vnd.docker.plugins.v1.1+json"
defaultTimeOut = 30
)
type remoteError struct {
method string
err string
}
func (e *remoteError) Error() string {
return fmt.Sprintf("Plugin Error: %s, %s", e.err, e.method)
}
// NewClient creates a new plugin client (http).
func NewClient(addr string, tlsConfig tlsconfig.Options) (*Client, error) {
tr := &http.Transport{}
c, err := tlsconfig.Client(tlsConfig)
if err != nil {
return nil, err
}
tr.TLSClientConfig = c
protoAndAddr := strings.Split(addr, "://")
sockets.ConfigureTCPTransport(tr, protoAndAddr[0], protoAndAddr[1])
scheme := protoAndAddr[0]
if scheme != "https" {
scheme = "http"
}
return &Client{&http.Client{Transport: tr}, scheme, protoAndAddr[1]}, nil
}
// Client represents a plugin client.
type Client struct {
http *http.Client // http client to use
scheme string // scheme protocol of the plugin
addr string // http address of the plugin
}
// Call calls the specified method with the specified arguments for the plugin.
// It will retry for 30 seconds if a failure occurs when calling.
func (c *Client) Call(serviceMethod string, args interface{}, ret interface{}) error {
var buf bytes.Buffer
if err := json.NewEncoder(&buf).Encode(args); err != nil {
return err
}
body, err := c.callWithRetry(serviceMethod, &buf, true)
if err != nil {
return err
}
defer body.Close()
if err := json.NewDecoder(body).Decode(&ret); err != nil {
logrus.Errorf("%s: error reading plugin resp: %v", serviceMethod, err)
return err
}
return nil
}
// Stream calls the specified method with the specified arguments for the plugin and returns the response body
func (c *Client) Stream(serviceMethod string, args interface{}) (io.ReadCloser, error) {
var buf bytes.Buffer
if err := json.NewEncoder(&buf).Encode(args); err != nil {
return nil, err
}
return c.callWithRetry(serviceMethod, &buf, true)
}
// SendFile calls the specified method, and passes through the IO stream
func (c *Client) SendFile(serviceMethod string, data io.Reader, ret interface{}) error {
body, err := c.callWithRetry(serviceMethod, data, true)
if err != nil {
return err
}
if err := json.NewDecoder(body).Decode(&ret); err != nil {
logrus.Errorf("%s: error reading plugin resp: %v", serviceMethod, err)
return err
}
return nil
}
func (c *Client) callWithRetry(serviceMethod string, data io.Reader, retry bool) (io.ReadCloser, error) {
req, err := http.NewRequest("POST", "/"+serviceMethod, data)
if err != nil {
return nil, err
}
req.Header.Add("Accept", versionMimetype)
req.URL.Scheme = c.scheme
req.URL.Host = c.addr
var retries int
start := time.Now()
for {
resp, err := c.http.Do(req)
if err != nil {
if !retry {
return nil, err
}
timeOff := backoff(retries)
if abort(start, timeOff) {
return nil, err
}
retries++
logrus.Warnf("Unable to connect to plugin: %s, retrying in %v", c.addr, timeOff)
time.Sleep(timeOff)
continue
}
if resp.StatusCode != http.StatusOK {
remoteErr, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, &remoteError{err.Error(), serviceMethod}
}
return nil, &remoteError{string(remoteErr), serviceMethod}
}
return resp.Body, nil
}
}
func backoff(retries int) time.Duration {
b, max := 1, defaultTimeOut
for b < max && retries > 0 {
b *= 2
retries--
}
if b > max {
b = max
}
return time.Duration(b) * time.Second
}
func abort(start time.Time, timeOff time.Duration) bool {
return timeOff+time.Since(start) >= time.Duration(defaultTimeOut)*time.Second
}